The demand for personal computers and related equipment continues to expand due to a number of factors. One important factor is that the prices of computers continue to decline. Another factor is the expansion and development of the Internet and related network communications. Increasingly, commercial and non-commercial enterprises are conducting business via the Internet and consumers need personal computers to gain access to the products and information that are available on the Internet. In addition to being more affordable, advances in computer application software, operating systems and communications software has fueled the development of computers having greater processing speeds and capacities. At the same time, the pressure to at least maintain, or preferably reduce, the physical size of the computer has increased as well. Accordingly, downsizing and miniaturization of computer components is an issue of great importance in the industry.
In an effort to reduce the form factor of the typical personal computer, and yet expand the capabilities of that computer, manufacturers began to develop miniature portable expansion devices having smaller sizes, such as add-on memory cards and modems. The typical expansion device was designed to plug into a port or socket on the main computer; thus the expansion device served to expand the capability of the computer without significantly increasing the size of the computer's physical envelope.
While the development of portable expansion devices represented a significant advance in the capabilities of personal computers, one drawback of many of the devices was that they were designed to fit only one manufacturer's computer, and thus were not interchangeable between platforms. The industry recognized that standardization of these devices would, among other things, greatly increase the demand for them. To this end, several manufacturers collaborated to form the Personal Computer Memory Card International Association (PCMCIA). This body develops and promulgates standards for the physical design, dimensions, and electrical interface of expansion devices. Now, many computers being manufactured, especially those having a reduced size, such as notebooks, have been adapted to accommodate these standards.
PCMCIA cards have become very popular because of their relatively small size, interchangeability, and capability. However, as a result of the relentless drive for smaller and more capable computers, the industry developed a new generation of expansion devices with an even smaller form factor than that of PCMCIA cards. The new expansion devices, or cards, are sometimes referred to as “compact flash” or “miniature flash” cards. Some examples of the new devices include SmartCard, SmartMedia (SSFDC), Memory Stick, and MultiMediaCard (MMC) and Secure Digital (SD) Flash. These compact devices have a very small “form factor” or physical size. SmartCards are about the same size as a credit card. SmartMedia cards are about one-third the size of a standard PC card and only 0.76 mm thick. Memory Stick cards are about the size of a stick of gum and are 2.8 mm thick. MMC and SD cards are about the size of a postage stamp. MMC cards are 1.4 mm thick, while SD cards are slightly thicker, about 2.1 mm think. In contrast, a typical card built to PCMCIA standards is about 86 mm long by 54 mm wide.
Until recently, there were only two (2) ways for a user to access a media card, depending on the system implementation. The most common way was through the use of an adaptor card that contains logic to translate from the media card interface to the PC card interface. This method was good in that it used the existing PC card slot on the notebook. However, these adaptor cards were very expensive because of the translation logic on the adaptor card. FIG. 1 diagrammatically illustrates a system 100 with a media card adaptor 110 that contains its own controller 120 in accordance with the art. Media card 115 is inserted into media card adaptor 110. The combination is then inserted into card slot 105. The other method was for the system to have a slot specifically dedicated to the media card. In such a system, the media card controller was either a dedicated chip or a separate function of an existing chip. The problem with this method was that the system must have additional space for the separate chip and media card slot. Since there are several different types of media cards available, this solution was undesirable because it restricted the user to a certain type of media card. FIG. 2 diagrammatically illustrates a system 200 with a dedicated media card slot 210 and controller 220 in accordance with the art. While other cards 225 are inserted into card slot 105, media card 215 is inserted into dedicated media card slot 210. Each different type of media card 215 would require its own dedicated media card slot 210 and controller 220. If a consumer had, for example, four (4) different types of media cards 215, the consumer's notebook would have to have four (4) different media card slots 210 with each with its own controller 220 in order for the consumer to use all four (4) media cards 215.
The PCMCIA has now developed CardBus Plus, defining a new way to interface several flash media and smart cards using the PCMCIA sockets that have become standard on notebook computers. Primarily, CardBus Plus integrates the media card translation logic onto the existing PC card controller inside the notebook. This allows for inexpensive, passive adaptors for the media cards. Although all passive adaptor cards will use the same form factor as existing 16-bit and CardBus cards, the card detect logic in the controller will determine if the inserted card is a 16-bit card, a CardBus card or a passive adaptor. The controller will then route the appropriate signals to a 68-pin PC card interface. FIG. 3 diagrammatically illustrates a passive adaptor system 300 with its media card logic 320 on an existing PC card controller 330 internal to a notebook in accordance with the art. Media card 315 is inserted into passive adaptor 310. The combination is then inserted into card slot 105. Card slot 105 would be capable of accommodating all cards with form factors that match existing 16-bit and CardBus cards.
Utilizing the CardBus Plus approach, a passive adaptor can be used to interface a given type of flash media to the PC. Each type of flash media has its own passive adaptor. For example, to interface a SmartCard to a notebook, a SmartCard can be inserted into a SmartCard passive adaptor which is then inserted into the notebook's existing PCMCIA socket (a single common port). As compared to other adaptors, a passive adaptor is very low cost. FIG. 4 diagrammatically illustrates a conventional PCMCIA card 400, with a portion of its casing removed, in accordance with the art. It can be seen from FIG. 4 that there are a number of different components, such as ICs, resistors and voltage regulators, that comprise PCMCIA card 400. These different components increase the cost of PCMCIA cards. By comparison, FIG. 5 diagrammatically illustrates a conventional passive adaptor 310 in accordance with the art. Passive adaptor 310 is basically comprised of signal traces routed to a connector. While passive adaptor 310 may still use some diodes and resistors, the cost of a passive adaptor, such as passive adaptor 310, is much less than the cost of non-passive media, such as PCMCIA card 400.
Although CardBus Plus standardized the use of passive adaptors, it still left at least one major problem. As noted above, each type of flash media card requires its own dedicated passive adaptor. This means that if, for example, a consumer has four (4) different types of flash media cards, the consumer will also need four (4) different passive adaptors in order to use all four (4) flash media cards with a notebook.
It is therefore desirable to provide a solution that enables the use of a single passive socket for multiple types of flash media cards. The present invention provides this by implementing circuitry with detection schemes that notify the host's controller of the type of media card that has been inserted. This circuitry and detection schemes can be designed to meet PCMCIA CardBus Plus standards.